'Playing like a girl' quotes insulting

Why is it that seemingly every recent story concerning UW-Green Bay men's basketball quotes someone saying that "playing like a girl" (or something similar) equates to a lack of toughness? Does anyone in the culture of boys and men's basketball realize that it is not OK to reference an entire demographic group as a derogatory term? Shouldn't everyone be offended when half of the population is repeatedly put down as weak? Have any of these men actually watched any girls or women's basketball? Are they aware of the quality of the UW-Green Bay women's basketball team? Did they see the local high school girls' teams winning state basketball titles this year? Where is any sign of weakness in any of that? Shouldn't telling a boy that they are "playing like a girl" be aspirational instead of insulting?